Q&A with Brookfield

Get Answers to Your Texture Questions

What's your texture challenge?

02/2014

CUSTOMER CHALLENGE: We are trying to measure the consistency of our salad dressings, which range from the consistency of mayonnaise to thick and creamy blue cheese dressings. We use different T-bar spindles with the Helipath Stand on a rotational viscometer to make a viscosity measurement. Each test takes about 3 minutes to set up, run, and clean up after. The viscosity data can vary considerably within a single test, especially for the dressings with particles and chunks; we are not sure which viscosity value to use. Is there an alternative way to do this test that takes less time and involves only one spindle choice?

BROOKFIELD ANSWERS:

Since you are testing for consistency, the Texture Analyzer provides a much quicker method. You can choose between two different types of probes: the TA-MP wire mesh probe and the TA43 spherical ball probe. The Texture Analyzer pushes the probe down into the dressing at a defined rate of speed, perhaps 2mm/sec, and measures the load force in grams, which is the dressing’s resistance to being displaced. The load reaches a steady state value within seconds as the probe becomes fully immersed. This is a much simpler test, it’s quicker to perform, the load force value is fairly constant, and the clean up afterwards is easy. You can do everything in less than 1 minute.

Submitted by: Anonymous

12/2013

CUSTOMER CHALLENGE: We are a manufacturer of pharmaceutical products encapsulated in soft-shell gelatin capsules. It may become necessary for us to produce our own gelatin capsules in the future to accommodate certain formulations. What is meant when the gelatin industry uses the term "Bloom Strength"?

BROOKFIELD ANSWERS: The Gelatin Manufacturers Institute of America has defined a procedure for measuring the strength of a gelatin formulation as follows:

A water solution consisting of 6.67% gelatin (7.50 +/- 0.1g gelatin and 105.0 +/- 0.2g deionized water, melted at 60-65°C) is prepared in a 150 mL, wide-mouth, glass bottle, which is then placed in a chilled water bath and held at 10+/- 0.1°C for 17 +/- 1 hours. After chilling, the rigidity of the gel is measured as the force, in grams, required to impress a standard 0.500 +/- 0.001 inch diameter cylindrical plunger (Bloom probe) to a depth of 4 millimeters into the surface of the gel. This force measurement is referred to as the gel strength, or Bloom rating, of the gelatin. The greater the force required, the higher the strength of the gel. Commercial gelatins range from 50 to 300 Bloom grams.

One type of instrument that measures Bloom strength is the Brookfield CT3 Texture Analyzer. After the Bloom probe makes contact with the gelatin, the instrument automatically moves the probe a distance of 4mm into the material at a rate of 0.5mm/sec. The measured force increases until reaching a peak value at the final depth of 4mm. This measured force value on the instrument display is the Bloom strength.

Submitted by: anonymous

10/2013

CUSTOMER CHALLENGE: When should I use a single stroke compression test vs. the double stroke characteristic of Texture Profile Analysis (TPA)?

BROOKFIELD ANSWERS: Most materials are tested successfully with a single stroke compression test. The maximum force (also known as “peak load”) measured by the probe during the compression cycle is the important parameter. Examples include:

a) the penetration force measured by a Magness Taylor punch probe when it ruptures the skin of a fresh apple
b) the cohesiveness of a bilayer tablet when sheared by the blade in the guillotine fixture
c) the firmness of yogurt when a ball probe pushes down into a container
d) the hardness of a chewy health bar when cut by a shear blade

TPA is appropriate for materials that try to recover their original shape. Squeezing a bread roll or pressing down on a slice of bread are typical examples. Both will bounce back to some degree after being compressed with a cylinder probe. On the second compression stroke, the probe will travel a greater distance before making contact with the object. The change in shape of the item (the distance that it compresses after the first stroke) is measured and is used in established calculations for "springiness" and "chewiness".

Submitted by: anonymous

09/2013

CUSTOMER CHALLENGE: Is there a "best practice" for selecting the probe travel speed when performing a texture test?

BROOKFIELD ANSWERS: A practical approach is to consider the application that you simulating with the Texture Analyzer. For example, if the action is squeezing a bread roll in your hand, then a probe speed of 1 to 3 mm per second for the large diameter cylinder probe is a good choice. Another example, like the settling of fruit pieces in a yogurt container, requires a very slow probe rate, perhaps 0.1 mm per second for the ball probe. A third example, like chopping vegetables with a blade, would use a rapid speed such as 10mm per second for the blade or wire probe.

If the objective is to establish a QC test procedure, then any speed may be appropriate. This suggests that trial and error be used to establish a speed that provides repeatable test results. One practical consideration in setting up the QC method is to minimize test time by selecting a probe speed that allows the test to complete in the smallest amount of time possible.

Submitted by: anonymous

09/2013

CUSTOMER CHALLENGE: Is there a maximum distance that a probe should penetrate an object during a compression test?

BROOKFIELD ANSWERS: Run several tests on the object with a penetration distance that does not exceed half of the item's thickness. For example, a candy bar that is 20mm high, suggests using a penetration distance up to 10mm in order to evalute the filling in the interior of the bar. If the objective is to evaluate only the chocolate coating around the candy bar, then the penetraion distance would be much smaller, perhaps 2mm. It is possible to penetrate the object to more than half of its thickness, but there is a risk that "base effects" from the table supporting the object may influence the load readings.

Submitted by: anonymous

07/2013

CUSTOMER CHALLENGE: Does the pharmaceutical industry use Texture Analyzers?

BROOKFIELD ANSWERS: There are a variety of established tests to consider. Hardness of tablets and capsules is measured by crushing the object in a compression test. Integrity and strength of the gel capsule shell is evaluated with a tension test. Coatings on tablets can be tested for adhesion. Actuation force to squeeze medical ointments out of tubes is evaluated with an extrusion test. There are special fixtures that have been designed to handle the sample for each of these test methods. The reason for these types of tests is to ensure that consumer expectations are met when handling or consuming the pharmaceutical item.

Submitted by: anonymous

06/2013

CUSTOMER CHALLENGE: When does it make sense to use a Texture Analyzer instead of a Viscometer?

BROOKFIELD ANSWERS: When investigating the mouth feel of a food item during chewing, the Texture Analyzer is the obvious choice because it can simulate the grinding action of the molar teeth. The same applies to the use of your hands when squeezing a food item, like a hard roll or a piece of fruit. Similarly, poking and cutting a piece of meat, fish or poultry is best evaluated by a Texture Analyzer with shear blade or punch probe. In summary, the nature of the action under evaluation suggests the best tool to perform the test. Viscometers are the logical choice for liquids, Texture Analyzers for solids, and either may be considered for soft-solid materials.

Submitted by: anonymous

04/2013

CUSTOMER CHALLENGE: How can we analyze the mayonnaise texture?

My questions are related to Mayonnaise, that are:

1. How can we analyze the mayonnaise texture?

2. At what temperature we should measure mayonnaise viscosity through offline Brookfield viscometer? (generally we cool mayonnaise from 29 degree Celsius to 25 Degree Celsius)

3. How can we reduce handling error for Viscosity measurement through Brookfield Viscometer?

BROOKFIELD ANSWERS: Thank you for your inquiry.

Viscosity measurement of mayonnaise has traditionally been accomplished with Brookfield T-Bar spindle and Helipath Stand accessory when using Brookfield viscometer with RV Torque Range. New methods allow for use of vane spindle with Brookfield DV3 Rheometer to measure the yield stress in mayonnaise as well as the viscosity.

Texture measurement of mayonnaise is performed with CT3 Texture Analyzer and choice of various fixtures, depending on the physical property of interest. The TA-STF measures spreadability. The TA-DEC measures extrusion. And the TA-MP measures consistency.

Go to the Brookfield website to see images of the above items: www.brookfieldengineering.com.

CUSTOMER CHALLENGE: When I perform multiple cycle tests, I don't see the same results in stand alone mode that I see when using the software, why?

BROOKFIELD ANSWERS: When running a test consisting of multiple cycles you will get three results in standalone mode. They are peak hardness (highest peak of all cycles), hardness of the last peak, and the standard deviation of all peaks. At this time, the TexturePro CT software only provides the hardness of the first peak and the average of all cycle peaks.

Submitted by: anonymous

CUSTOMER CHALLENGE: We are occasionally asked, what is the safe temperature range for our texture probes?

BROOKFIELD ANSWERS:The answer depends upon which probe. Our plastic probes come in two types of material. They are clear acrylic and black delrin. The temperature range for each probe is as follows:

  • Acrylic Service Temperature – (0F -150F)
  • Delrin Service Temperature – (-40F to 185F)

Submitted by: anonymous

CUSTOMER CHALLENGE: Can the CT3 be connected to a printer or an external computer via the USB or RS232 ports?

BROOKFIELD ANSWERS: No data comes out of either the USB or RS232 port in standalone mode. Data is only available at these ports when running with Texture Pro CT software. We occasionally field related questions whenever customers consider connecting to a PC and writing their own data acquisition software. This is impractical and should be discouraged.

Submitted by: anonymous